Often after I watch a movie I'll look up an old Pauline Kael review of it to see what she had to say. Pauline, who once applied the term "schlocky romanticism" to Casablanca, pretty much hated everything except the original version of Lolita (which nobody else liked) and, surprisingly, the first two versions of Invasion of the Body Snatchers. (She really dug the 1978 version: "Undiluted pleasure and excitement.") From 5001 Nights at the Movies, here is her review of the 1956 version of the film:
"A B-picture classic. This plain and inexpensive piece of science fiction employs few of the resources of the cinema (to put it mildly), but it has an idea that confirms everyone's suspicions. People are being turned into vegetables--and who can tell the difference? Kevin McCarthy and Dana Wynter, who try to cling to their animality and individuality, seem inexplicably backward to the rest of the townspeople. Some of the best lines of dialogue are voice-overs--the chatter of the dehumanized. Directed by Don Siegel...with Carolyn Jones, Larry Gates, and Sam Peckinpah (who worked on the script) in a few bits. Based on a Collier's serial by Jack Finney."